This invention relates to cables for sensing the presence of a corrosive liquid.
Transporting liquids such as crude oil, refined petroleum products, or corrosive liquids such as concentrated acids or bases is often accomplished utilizing tanks and underground pipelines. Underground pipelines are subject to leakage from the piping, fittings, and valves. When an underground pipe carrying a hazardous or corrosive liquid develops a leak, the leak must first be detected and located before it can be repaired.
Various systems for detecting leaks are well-known. For example, sensor cables may be used to detect changes in variables along an elongate path, such as the presence of a liquid such as water, an organic solvent, or a corrosive liquid. Sensor cables may be extended in a pipeline, along the length or longitudinal axis or at various sections or points at which the leakage of liquids tends to occur.
Known sensor cables generally comprise first and second conductors spaced apart from one another. If an electrically conductive liquid contacts both the first and second conductors, an electrical connection is made. If there is not enough liquid present to create contact between the first and second conductors there will be no connection. Conventional sensor cables will detect any conductive liquid, including rainwater and groundwater. Therefore, these sensor cables are subject to false alarms since such conventional sensor cables are not capable of differentiating between common conductive liquids such as ground water or rainwater containing mild concentrations of corrosive components and conductive, highly corrosive, liquids such as concentrated sulfuric acid, hydrochloric acid, nitric acid, acetic acid, strong mineral acids, or strong bases such as sodium hydroxide.
It is an object of this invention to provide a cable particularly suitable for detecting the location of a leak.
It is a further object of this invention to provide a method of detecting and locating the presence of a leak utilizing the cable of the present invention.
The present invention relates to a cable particularly suitable for detecting corrosive liquids and for detecting and locating leaks and a method of using the cable. In more detail the cable of the current invention comprises first and second sensing wires and a core member around which the first and second sensing wires are wrapped. Further, each sensing wire comprises a center conductor and at least one conductive layer. At least one of the sensing wires further comprises at least one non-conductive surface layer. The cable may further comprise insulating wires to assist in determining the exact location of the leak.
An alternate embodiment of the cable comprises first and second sensing wires and a core member around which the first and second sensing wires are wrapped. The first and second sensing wires and the core member are encapsulated by at least one non-conductive surface layer. The cable may further comprise insulating wires to assist in determining the exact location of the leak.
The cables of the present invention may be useful as part of an electrical circuit to detect the location of leaks. The present invention also relates to a method of using the cables to detect and locate the presence of a leak.